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  • DMARC

    How to Route DMARC Aggregate Reports to a Third-Party Service Without Direct Email Delivery

    Direct email delivery for DMARC reports is messy — spam filters, mailbox capacity, firewall rules. Here's how to route reports from your DNS host to a third-party aggregator instead.

    DMARCGuardian Editorial Team · May 11, 2026

  • Deliverability

    Why FBL Complaints Persist on Transactional Email Even When Content Is Legitimate

    Persistent feedback loop complaints on legitimate transactional email usually come down to one missing header. Here is what causes them and how to fix them.

    DMARCGuardian Editorial Team · May 11, 2026

  • DMARC

    Why Your DMARC Reports Show Reject Records for Non-Existent Gov.uk Subdomains

    If your DMARC aggregate reports show reject records for gov.uk subdomains you do not own, here is why that happens and what it actually means.

    DMARCGuardian Editorial Team · May 11, 2026

  • Deliverability

    How Phishing Sites Are Using Let's Encrypt Certificates on Raw IP Addresses to Bypass Security Filters

    Phishing campaigns are using Let's Encrypt certificates on raw IP URLs to evade security filters that historically flagged plain HTTP IPs. Here's how the attack works and what defenders should watch for.

    DMARCGuardian Editorial Team · May 11, 2026

  • DMARC

    Why Most Email Gateways Miss Phishing PDFs That Use /OpenAction to Launch Attacker URLs

    Email security gateways don't scan PDF action dictionaries by default. A clean-looking PDF with a single /OpenAction pointing to a malicious URL can land in inboxes with no warning.

    DMARCGuardian Editorial Team · May 11, 2026

  • DMARC

    Why Publishing p=reject Without sp= Still Leaves Your Subdomains Open to Spoofing

    Publishing p=reject without the sp= tag leaves subdomains unguarded at many receivers. Here's why it happens, how attackers exploit it, and the three fixes that close the gap.

    DMARCGuardian Editorial Team · May 11, 2026

  • DMARC

    What Happens to Email Authentication When ARC Is Retired?

    ARC (Authenticated Received Chain) is being retired from email standards. Here's what that means for forwarded mail, mailing lists, DMARC, and what you should do before the change takes effect.

    DMARCGuardian Editorial Team · May 10, 2026

  • DMARC

    Why Your DMARC Aggregate Reports May Not Be RFC 7489 Compliant (And What to Do About It)

    Most DMARC aggregate reports contain RFC violations that cause standard parsers to fail silently. Here's what's broken and how to handle it.

    DMARCGuardian Editorial Team · May 10, 2026

  • DMARC

    How to Add DMARC Monitoring to Your MSP SIEM Stack (Practical Guide)

    MSPs can add DMARC monitoring to their existing SIEM stack using three approaches: native tool APIs, IMAP/SMTP report ingestion, or syslog/webhook forwarding. This guide covers all three with a practical implementation checklist.

    DMARCGuardian Editorial Team · May 10, 2026

  • DMARC

    Why Your DMARC Report Shows DKIM Fail and SPF Pass at the Same Time

    DKIM fail and SPF pass together in a DMARC report is normal, not broken. Here's what alignment means, why it happens, and what to do about it.

    DMARCGuardian Editorial Team · May 10, 2026

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